CA2189846A1 - Continuously variable hydrostatic transmission - Google Patents
Continuously variable hydrostatic transmissionInfo
- Publication number
- CA2189846A1 CA2189846A1 CA002189846A CA2189846A CA2189846A1 CA 2189846 A1 CA2189846 A1 CA 2189846A1 CA 002189846 A CA002189846 A CA 002189846A CA 2189846 A CA2189846 A CA 2189846A CA 2189846 A1 CA2189846 A1 CA 2189846A1
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- continuously variable
- control
- manifold
- radial face
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H39/00—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution
- F16H39/04—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit
- F16H39/06—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type
- F16H39/08—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders
- F16H39/10—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing
- F16H39/14—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing with cylinders carried in rotary cylinder blocks or cylinder-bearing members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H39/00—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution
- F16H39/04—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit
- F16H39/06—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type
- F16H39/08—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders
- F16H39/10—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H39/00—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution
- F16H39/04—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit
- F16H39/06—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type
- F16H39/08—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders
- F16H39/10—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing
- F16H2039/105—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motor and pump combined in one unit pump and motor being of the same type each with one main shaft and provided with pistons reciprocating in cylinders with cylinders arranged around, and parallel or approximately parallel to the main axis of the gearing at least one pair of motors or pumps sharing a common swash plate
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Reciprocating Pumps (AREA)
- Control Of Fluid Gearings (AREA)
- Control Of Transmission Device (AREA)
- Steroid Compounds (AREA)
- Structure Of Transmissions (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
Abstract
A continuously variable hydrostatic transmission includes an input shaft connected to drive a hydraulic pump unit, a grounded hydraulic motor unit, and an output shaft. A wedge-shaped swashplate is pivotally mounted to the output shaft in driving connection to receive output torque resulting from the exchange of pressurized hydraulic fluid between the pump and motor units through ports in the swashplate. A hydraulically actuated ratio controller is pivotally linked to the swashplate to selectively adjust the swashplate angle relative to the output shaft axis and thereby change transmission ratio.
Description
~WO 96/31715 2 1 8 9 ~ 4 6 , PCT/US96/01674 CONTINUOUSLY VARIABLE lIYDROSTATIC TRANSMISSION
RErCRE~/CE TO RELATED APPLlCATlONS
The inYention disdosed in this ~a~F" " has particular, but not ne.,~asa~ limited, ~ to the continuously vâriable l l~l us~dlk~
IldllSIll;SSiO(ls disclosed in co-pending U.S. Patent A, r~ 5~ Serial Nos.
û81093,192, filed July 13, 1993; 08/333,688, filed November 3, 1994; and 081342,472, filed November 21, 1994. The disclosures of these .~ 5 are i,,cu,~,u,d~ed herein by reference.
FIELD OF THE INVENTION
The present invention relates to hydraulic machines and, more 1û particularly, to ll~ lldl)slllii.aiulls capable of llallallli;tillg powerfrom a prime mover to a load at continuously (infinitely) variable transmission ratios.
BACKGROUND OF THE INVENTION
In my cited U.S. PatentApplication Serial No. 081093,192, a hydraulic machine is disclosed as including a hydraulic pump unit and a hydraulic motor unit positioned in opposed, axially aligned relation with an i"~. ",edi~ , wedge-shaped 5~ I,UId~ The pump unit is ..u", ,eul~d to an input shaff driven by a prime mover, while the motor unit is grounded to the stationary machine housing. An output shaff, coaxial with the input shaff and 20 drivingly coupled to a load, is pivotally conne~ d to the s~ ldld in torque coupled relation. When the pump unit is driven by the prime mover, hydraulic fluid is pumped back and forth between the pump and motor units through ports in the s~dall~ldld. As a result, three torque c~",pone"~a, all acting in the same direction, are exerted on the swdallpld~d to produce 25 output torque on the output shafl for driving the load. Two of these torque cu",pol~e"la are a Ille~,lldlliudl Cu~pol1e~1 exerted on the swaal,pldld by the rotating pump unit and a hydro-mechanical c~""~on~"l exerted on the s~,a~l,, ' ' by the motor unit. The third component is a pure ll~dlualdlic WO9613171S 2 1 8 9 846 2 - PCI~ S96101674 colllpo~ "l resulting from the ~irrcllc,,,liàl forces created by the fluid pressures acting on circu",' ~:"li. :`y opposed end surfaces of the s.._Ol,,uldl~ ports, which are of different surface areas due to the wedge shape of the sw~l ",!at,_.
To change t, d"a" ,;~ ratio, the angular ori~"' ' ~ of the sv, ~;,l ,~,l relative to the axis of the output shafl is varied. Since the l, dl lal I l;SSiOI~ ratio, i.e., speed ratio, is continuously variable, the prime mover can run at a constant speed set esse"li~ at its most efficient operating point. The y of a 1:0 (neutral) I,d"a",;~_;al~ ratio setting eliminates the need for a clutch. Unlike c~,)J~.,tional, continuously variable ~l~dlus~d~k~
~l al lal I ,issio, 15, wherein hydraulicfluid flow rate increases p, upo~ ~iu, Id~ly with increasing ~,d"a,l,;ssion ratio such that maximum flow rate occurs at the highest ~,d"a",;~aion ratio setting, the flow rate in the hydraulic machines disclosed in my cited U.S. ~rr'- " ~S reaches a maximum at a midpoint in the ratio range and then progressively decreases to esse,~ia:'y zero at the highest ~Idll~lll;.~aiUn ratio setUng. Thus, losses due to hydraulic fluid flow are reduced, and the annoying whine of conventional hydrostatic ~,d"a",;ssiol~s at high ratios is avoided. By virtue of the multiple torque c~"",ol,el"a exerted on the s~a~ll,uldL~, the de,,,~asi"~ hydraulic fluid flow in the upper half of the output speed range, and the capability of acc~"""--' ,9 an optimum perF~""a"ce prime mover input, the hydraulic machine of my cited . r' ' I has a particularly advantageous appl;~,à~io as a highly efficient, quiet, continuously variable ll~dlualdtk, ~Idrlalllissioll in vehicular drive trains.
SUMMARY OF THE INVENrlON
An objective of the present invention is to provide improvements in the ll~dlua~d~ic lldl~alllk,siull disclosed in my cited U.S. rrF' " ~ Serial No.
08/093,192, to achieve ecollor"ies in size, parts count and manufacturing cost.
An additional objective of the present invention is to provide improvements in the manner in which low pressure makeup hydraulic fluid WO 96131715 2 1 ~ 9 ~ 4 6 PCI'I~S96101674 is introduced to a I~ uald~ic ~Idl~alll;ssiol1 and the manner in which hydraulic fluid pressure iâ made available to a ratio controller on setting and changing t,d,~s",;~aiol~ ratio.
A fur~her objective of the present invention is to provide improvements 5 in a controller for setting and changing the ratio of input speed to output speed of a ll~ lUSIdli~ iull in a continuously (infinitely) variable manner.
To achieve these objectives the hydraulic machine of the present invention in its ~ as a continuously variable hydrostatic û lldllslll;ssionl CUIllp~iS~a a housing; an input shaft journaled in the housing for receiving input torque from a prime mover; an output shaft journaled in the housing for imparting driving torque to a load; a hydraulic pump unit coupled to the input shaft; a hydraulic motor unit grounded to the housing;
a wedge-shaped SWd~l luld~e: including ports extending between an input face 15 cu~r~ul'~i''g the pump unit and an output face cu,,~lu,,ti,,g the motor unit; a coupling pivotally i,,lt:, u,,,,e~i,,g the s~.&~l,r and the output shaft in torque-coupled relation; and a 1, dl IC~ io~ ratio controller including a control cylinder positioned coaxial to the output shaft in surrounding relation to one of the pump and motor units and a control piston movably mounted by the 20 control cylinder and linked to the s~asl,pldl~: such that axial movement of the control piston is converted to ll dl~a~ kn~ ratio-changing pivotal motion of the s\~&sl,uldl~ about a pivot axis of the coupling.
AddiUonal features advantages and objectives of the invention will be set forth in the des., ; , which follows and in part will be apparent from the 25 d6s~ ,ti~"~ or may be learned by practice of the invention. The objectives and advd"ld~es of the present invention will be realized and attained by the apparatus particularly pointed out in the following written des-, iution and theappended claims as well as in the accu~,t,d"~i"g drawings.
It will be ulld~ ùod that both the foregoing gene!al des- ,iulion and 30 the following detailed dea~.,i '; ~ are exemplary and ~pldl~ ~.y and are intended to provide further e~pld,,dliùl~ of the invention as claimed.
WO 96/3171~ PCIIUS96/01674 2t8~846 -4-The a~ ul~lpd~ lg drawings are intended to provide a further ul~ ldll.lillg of the invention and are illuul,u~ldlt:d in and constitute a partof the ~Fe~ , illustrate a preferred embodiment of the invention and, together with the des~d i,u~iùl~, serve to explain the principles of the invention.
BRIEF DE:~Cfib I ION OF rHE DRAWINGS
Fig. 1 is a longitudinal secUonal view of a continuously variable lldllalll;~ structured in acc~"~ance with a preferred embodiment of the present invention;
Fig. 2 is an enlarged r,dy",~"ld~y, longitudinal sectional view of the 1û input end portion of the lldll~lll;ssiûl~ of Fig. 1 that ill~rf.u, ' ~ different sectional views of a manifold block.
Figs. 3 and 4 are plan views of opposed faces of a portplate seen in Figs. 1 and 2.
Fig. S is a plan view of one face of a manifold block seen in Figs. 1 and 2.
Fig. 6 is a schematic view of an external lldll:,lll;ssiol1 ratio control valve uUlized with the ll~dlu~dlic lldll~lll;~aiol1 of Figs. 1 and 2.
C~ ,uoll.li,ly reference numerals refer to like parts throughout the several views of the drawings.
DETAILED DtSÇP~" IIQN OF THE PREI L~RELI EMBODlMENr The continuously variable ll~llualdliu lldll~ iol~ according to the preferred ~Illbodi~ l of the present invention, generally indicated at 10 in Ule overall view of Fig. 1, comprises, as basic c~",uol~"l~, a housing 12 in which are journaled an input shan 14 and an output shan 16 in coaxial, generally end-to-end relation. The end of input shan 14 external to the housing is splined, as indicated at 14a, to facilitate driving col~l~eu~iùn tû aprime mover (not shown), while the end of output shan 16 external to the housing is splined, as indicated at 16a, to facilitate driving C~ u~iOIl to a load (not shown). Input shan 14 drives a hydraulic pump unit, generally indicated at 18. A hydraulic motor unit, generally indicated at 20, is grounded to housing 12 in axially opposed relation to pump unit 18. A
~WO96/31715 2 1 ~d q P~ 4 6 5 ~ 674 wedge-shaped s\._~h, ' ', generally indicated at 22, is drivingly uu""el,Led to the output shaft 16 in a position between the pump and motor units and is apertured, one aperture indicated at 23, to ac~,u"""odd~e e~.,l,allges of hydraulic fluid between the pump and motor units. A control piston 24 is 5 linked to s~. ~,u'_'~ 22 for the purpose of pivotally adjusting the angle of SWd~l 1, ' ' O(iél 1' " ~ relatiYe to the output shaft axis 25, thereby adjustably setting the ~ldllalllis~siol~ ratio of the input shaft speed to the output shaftspeed.
Now referring jointly to Figs. 1 and 2 in greater detail, the cylindrical 1û housing 12 includes a cover 30 secured in place by an annular array of bolts, one seen at 31, to close off the open input end of the housing. Input shaft 14 extends into housing 12 through central openings in the cover and a manifold assembly, generally indicated at 34, that is secured in place between the cover and housing by the bolts 31. Bearings 35, fitted in the 15 cover and manifold assembly openings, joumal the input shafl 14 for rotation. An annular end cap 36, afffixed to cover 30 by bolts 37, holds a seal 38 against the input shaft peripheral surface to prevent leakage of hydraulic fluid.
As best seen in Fig. 2, the inner end of input shaft 14 is counterbored 20 to provide a cylindrical recess 40 for receiving a reduced diameter inner terminal pûrtion 42 of output shafl 16. A roller bearing ring 44, fitted in recess 40, provides inner end joumal support for the output shaft. The inner terminal portion of input shaft 14 beyond a hub member 45 of manifold assembly 34 is flared to provide a radial flange 47 having a splined 25 peripheral surface in meshed e"~ag~"~e"l with a splined central bore ~commonly indicated at 48) of an annular thrust washer 49. An annular portplate 50 is positioned between manifold assembly 34 and thrust washer 49.
The right radial face of thrust washer 49 is recessed to receive the 3û radially fiared left end portion of a carrier 56 for a plurality of pistons included in hydraulic pump unit 18. These pistons, for example, ten in number with . _ _ _ _ . _ . . . .
WO 96/31715 ~ .'OIC74 one being generally indicated at 58, are uniformly distributed in a circular array cu~)c~ iu with output shaft axis 25 in the manner disclosed in my dted patent ~,~, ' " ns. As illustrated in Fig. 2 herein, each pump piston 58 includes a piston head 6û mounted to the piston carrier 56 by an 5 elongated bolt 61 extending through a hole in the piston carrier and threaded into a tapped hole in thrust washer 49, as indicated at 49a. Piston head 6û
is machined to provide a spherical inner surface cc,,,tu,,,,i,,g to a spherical outer surface of an annular bearing 62 keyed on a bushing 63 carried by bolt 61. A standoff sleeve 64 is also carried on bolt 61 such that, when th-~ bolt 1û is tightened down, bushing 63 is clamped in place to app,u~i.,t~,ly pc~sitionbearing 62 and piston head 6û in axially spaced relation to piston carrier 56.
As a result, each piston head 60 is mounted for limited radial and swivel motions.
The cylindrical right end portion of pump piston carrier 56 carries an 15 annular spherical bearing 66 . ur,fu, " ,i"~ to a spherical surface 67 machined in the central opening of an annular pump cylinder block 68. An annular uu~ ul tlaaion spring 69 acting against axlally opposed shoulders provided on carrier 56 and spherical bearing 66 urge the spherical bearing rightward toward the output end of lldllalll;~a;ûn. A roller bearing ring 70 is confined 20 in the central opening of pump piston carrier 56, through which output shaft 16 extends, to provide joumal support for pump piston carrier 56. Cylinder block 68 Includes an annular array of pump cylinders 72 for ,~st,e.,lh~cly receiving the pump pistons 58. By virtue of the spherical bearing mountings of pump piston heads 60 and pump cylinder block 68"~, ~aail ,~ motion of 25 the pump cylinder block axis relatlve to output shaft axls 25 is accullllll~
Retuming tû Fig. 1, hydraulic motor unit 20 is ess~,.ti~.l'y structurally equivalent to hydraulic pump unlt 18. However, an annular motor piston carrier 74, equivalent to rotating pump piston carrier 56, is instead grounded 30 to housing 12 by an annular array of bolts 75. These bolts also serve to mount motor pistons, generally indicated at 76, each including a piston head WO 96131715 PCI'IUS96/01674 ~ 7 ~
21 8~46 77 swivel mounted on a spherical bearing 78 positioned in standoff relation to pump piston carrier 74 by a sleeve 79 in the same manner as pump pistons 58. A motor cylinder block 80 is then swivel mounted on carrier 74 via an annular spherical bearing 82. An annular co~ saoiol~ spring 83 urges spherical bearing 82 leftward toward the input end of 1, dl ,a",;o,~;~n 10.
Again, as in the case of pump cylinder block 68, a circuiar array of motor cylinders 84 are formed in cylinder block 80 to ~t:Opeuth~,ly receive motor pistons 76. Since motor unit 20 is grounded to housing 12 by bolts 75, the motor pistons 76 and cylinder block 80 do not rotate, however, the spherical bearing mountings of motor piston heads 77 to bolts 75 and motor cylinder block 80 to carrier 74 aCC~IIIIIIOdd~ nutating (~ aaillg) motion of the motor cylinder block axis.
As further seen in Fig. 1, output shaft 16 extends rightward through the central opening in motor piston carrier 74, where a supporting roller bearing ring 85 is positioned, and out of housing 12 through a central opening in a hub-shaped output end closure 86 affxed to housing 12 by bolts, one seen at 87. A roller bearing ring 89, positioned in the end closure central opening provide further journal support for the output shaft. An annular end cap 92, affixed to end closure 86 by bolts 93, confines a seal 94 against the surface of output shaft 16 at the point of final exit from the housing to prevent leakage of hydraulic fluid.
S~&ol, ' 22 is drivingly connected to output shaft 16 in operative position between pump unit 18 and motor unit 20 by transverse pins 96 (~ape~ received in did",~ ,a:'; opposed hubs 98 affixed to the output shaft. The common axis of pins 96~ ~, II "~go"al to the output shaf axis 25~
constitutes a pivot axls for S\li~dallp~ 22 to accommodate l~dna~l; ,sion ratio-change adjustment of the sv~dal Ir l ' angular ~, i~, l 'i~ n relative to the output shaf axis 25.
Returning to Fig. 2~ 5Wdoll,' ' 22 includes an input face 101 in intimate sliding contact with face 102 of pump cylinder block 68 and an output face 103 in intimate sliding contact with face 104 of motor cylinder WO 96131715 rCr/US96101674 21 8~846 -8-block 80. The input and output faces of sw~sl~, 22 are relatively oriented at an acute angle to proYide the wedged shape of the swdal,, Ports 23 extend between the input and output faces o~ the s~. h~ and communicate with respectiYe openings 107 into cylinders 72 of pump cylinder block 68 and respectiYe openings 108 into the cylinders 84 in motor cylinder block 80, all as more fully described and illustrated in my cited patent ~ ,~ 1S.
Ratio control piston 24 comprises a rightward cylindrical section 110 and a leffward cylindrical section 112 that are joined ess~"t;~:'y end to end by screw threads 113. The ratio control piston 24 is slidingly mounted on a control cylinder 114 that is proYided with a pair of didllle:tlica:!y opposed v~a,d'y extending ears 116 haYing apertures through which the 11, piYot pins 96 extend. The output end of piston section 110 is fommed with a pair of closely, angularly spaced tangs 118 that are apertured to mount the ends of a pin 120, which, in turn, piYotally mounts one end of a link 122 positioned between tangs 118 in closely spaced relation. The other end of link 122 is piYotally connected to a pin 124 that is carried by a pair of closely, angularly spaced tangs 126 in flanking relation to the link.
Tangs 126 are radially outward pluj~. tiUI la of a connector block 128 that is fitted in a recess 129 formed in S~dalllJId~ 22 and held in place by a transverse locking pin 130.
It is thus seen that axially, t~ ., Ul,d~il Iy movement of control piston 24 is translated into angular motion of the swaallpld~ as it piYots about its piYotal cc ""e~ (pins 96) to output shaff 16. It is also seen that, by Yirtue 25 of this c,nneliu" and the c~""e. tiOI1 of control cylinder ears 116 to the s~v~ ,u'..'~ pivot pins 96, control piston 24 and control cylinder 114 rotate in unison with output shaff 16. A free end segment 110a of control piston section 110 is machined to proYide an annularly distributed balancing mass for the purpose of co~", Lald~".i"g the eccentric masses of the s\. a~l Ipld~:
22, and the ,u, t:l eaaillg pump cylinder block 68 and motor cylinder block 80 as fully explained in my U.S. patent .~, 'ic.~ Serial No. 08/093,192.
.. _ . .. . . .. . . . . . .. . . . . . . .
Still refening to the enlarged view of Fig. 2, the lefl end of control cylinder 114 is fommed with a radially inwardly extending lip 132 that serves as an axial stop to engage portplate 50 ass6",bled within the control cylinder in a press-fit manner. A clamping ring 134, having a threaded periphery engaging an intemal threaded section 135 of control cylinder 114, is turned down to securely clamp portplate 50 against lip 132. Thus, annular portplate 50 also rotates in unison with output shaft 16.
The leflt end of control piston section 112 is machined to proYide an annular shoulder 140 that projects radially inward into sliding ell~dge",e"l with the peripheral surface of control cylinder 114. The control cylinder is machined to provide an annular shoulder 142 projecting radially outward into sliding el~gag~",t:"I with an inner cylindrical surface of control piston section 112. The space between control piston section 112 and control cylinder 114 that is axially defined by the opposed shoulders 140 and 142 provides an annular control chamber 146. Another annular control chamber 148 is provided by the radial spacing between the control cylinder and control piston section 112 that is axially defined by shoulder 142 and the input (lefl) end surface 149 of piston section 110. Seal rings 150 are i"c~l~,o,aled in shoulders 140 and 142 and piston section 110 to prevent hydraulic fluid leakage from chambers 146 and 148.
At angularly spaced locations, longitudinal bores are drilled into the left end of control cylinder 114 to provide fluid passages 152 (Fig. 1) and 154 (Fig. 2). Passage 152 1e~ alc:5 in a radial passage 153 to the output ~right) side of shoulder 142 and thus opens into chamber 148. Shorter passage 154 k"",;"ales in a radial passage 155 on the left (input) side of shoulder 142 and thus opens into chamber 146. The outer ends of passages 152 and 154 are plugged, as indicated at 156 in Fig. 2. As seen in Fig. 2, passage 154 communicates with a radial passage 158 drilled in portplate 50 via a short connector passage 159 drilled in control cylinder 114. Theinnerendofradialpassage158communicateswithalongitudinal passage 160 that, in tum, communicates with a shallow annular cavity 162 WO 96/31715 2 ~ 8 9 8 4 6 - 10 - PCIJUS96101674 formed in the input radial face 163 of portplate 50, as also seen in Fig. 3.
At a radius equal to that of cavity 162, a longitudinal passage 164 is drilled into an annular manifold block 166 press-fitted on hub 45 of manifold assembly 34. The left end of longitudinal passage 164 opens into a radial passage 168, whose outer end t~llllilld~:s at a port 170 in manifold block 166.
In the same manner and as illustrated in Fig. 1, longitudinal passage 152 in control cylinder 114 communicates with a radial passage 172, drilled in portplate 50, via a short connector passage 173 in control cylinde~ 114.
The inner end of radial passage 172 communicates with a longi~udinal passage 174 that opens into a shallow annular cavity 175 machined in the input radial face 163 of portplate 50 (Fig. 3). A longitudinal passage 177 is drilled into the right face of manifold block 166 at a radius equal to that of cavity 175. The inner end of passage 177 opens into a radial passage 178, whose outer end l~ illdl~s at a port 180 in the manifold block.
It is seen that, although portplate 50 rotates with the output shaff and man'lfold block 166 is grounded to housing 12 by bolts 31, the annular caviUes 162 and 175 in the portplate provide continuous fluid communication between the longitudinal passage 160 and 164 and between longitudinal passages 174 and 177, le:!3dlU~ of the angular relation of the rotating portplate and stationary manifold block. Thus, during 1, dl 1:~11 I;SSiOI) operation, port 170 is in continuous fluid communication with chamber 146, and port 180 is in continuous fluid communication with chamber 148.
To ensure an adequate supply of makeup hydraulic fluid from a sump pump 182, three additional ports are formed in manifold block 166 at 1200 angularly spaced positions. One of these makeup ports is iliustrated in Fig.
1 at 184. Each makeup port communicates with a radial passage 186 drilled in manifold block 166, which, in turn, communicates with an angular passage 188 that opens into the right radial face of the manifold block in c~l,r,~ 9 relation with an outermost semi-annular cavity 190 machined into the left radial face 163 of portplate 50, as seen in Fig. 3. A final manifold port 192, ~WO 96/31715 ~ 1 8 ~ 8 4 6 1 1 - PCr/US96/01674 seen in Fig. 2, communicates with a radial passage 193 in manifold block 166, which, in turn, communicates with a longitudinal passage 194 that opens into the right radial face o~ the manifold block in cu~rlul ," ,9 relationwith an annular cavity 196 machined in portplate face 163 (Fig. 3).
The relative angular and radial ~osiliol,i"~s of the manifold passages at the right radial face 199 of manifold block 166 are illustrated in Fig. 5. It is pointed out that the sections of manifold block 166, portplate 5û and control cylinder 114 illustrated in Figs. 1 and 2 have been chosen to best illustrate the hydraulic fluid flow l~ldliUI~ ,s of the various passages 1û therein, and thus do not represent their actual angular I~I'ioll~ll;ys, which, in the case of manifold block 166, can be seen in Fig. 5.
The right radial face 2ûû ûf portplate 5û, seen in plan view in Fig. 4, is machined to proYide a pair of didll~ y opposed, semi-annular (kidney-shaped) surface r~avities 202 and 204. A pair of kidney-shaped ports 206 proYide fluid communication between cavities 190 and 202 through portplate 50, while a pair of kidney-shaped ports 208 provide fluid communication between cavities 204 and 196, as also seen in Fig. 3.
Returning to Fig. 2, the pump piston mûunting bolts 61 are drilled with axial bores 210 (illustrated in phantom line), such that the fluid pressures in the pump cylinders 72 are communicated to separate recesses 212 formed in the lefl radial face of thrust washer 49 bearing against the right face 200 (Fig. 4) of portplate 50. Thus, the pump cylinder fluid pressures are communicated to surface cavities 202 and 204 in portplate face 200 and then to surface cavities 190 and 196 in portplate face 163 (Fig. 3) via ports 206 and 208.
When the pump pistons 58 and pump cylinders 72 revolve from the thinnest point of the wedge-shaped s~ l Ipldle: 22 around to its did" lell i.,.. 'y opposed thickest point, the volumes ûf the ~,o~ ' ?d pump cylinders ~I~Jylt7a~ cly decrease, and the hydraulic fluid in these pump cylinders is 30 therefore being pressurized. This is cùl~sid~ d to be the high pressure or pumping side of hydraulic pump unit 18.
WO 96131715 ~ .'OIC74 '21 8q846 12-Vvhen, the pump pistons and pump cyiinders revolve from the thickest point around to the thinnest point of the s~c~l,, ' ' 22, the volumes of the ~s ~ ' ' pump cylinders 72 are progressively expanded. This is sicl~ d to be the low pressure or suction side of the hydraulic pump unit 5 18.
Since portplate 50 and s~v;.~l Ir ' ' 22 rotate in unison, because both are Ued to output shaft 1 6, the angular, ~ t~ollsl ,ips of the portplate surface cavities to the high pcessure (pumping) and low pressure ~suction) sides of pump unit 18, as dt,l~""i"ed by the S~ Jldl~, remain fixed 1~9dl~ldaS of 10 input to output shaft speed ratio. The angular o~i~"' " ~ of portplate 50 relative to the sv/asl)pldL~: is such that the hydraulic fluid in portplate surface caviUes 190 and 206, introduced from by the sump pump 182 through manifold block ports 184 and passages 186, 188, assumes the average fluid pressure in the pump cylinders 72 involved in the suction side of pump unit 18 by virtue of the fluidic c~llllel,Lio,~a provided by bores 210 in the pump piston mounting bolts 61. The provision of three makeup passages 188 spaced 120 apart guarantees that at least two makeup ports are always in fluid communication with the 180 arcuate surface cavity 190 in the leflt radialface 163 of portplate 50 (Fig. 3). Consequently, starvation of hydraulic fluid 20 in pump unit 18 is prevented.
On the other hand, hydraulic fluid that has filled portplate surface cavities 196 and 204 through the bores 210 in the pump piston mounting bolts 61, is pressurized to an average of the fluid pressures in the pump cylinders 72 invoived in the high pressure (pumping) side of pump unit 18.
25 As described above, the high pressure hydraulic fluid in portplate cavity 196is in flow communication with port 192 through manifold passages 193 and 194.
A ratio control valve 220, such as illustrated in Fig. 6, is provided to stroke (change) tldlla",;i,aiLn 10 through a limited reverse speed range of 30 acute s~ ,;,p'..`~ angles COUIIL~ILIOCk~ of a S.Vr hr~ ' input (lefl) face 101 angle normal to the output shaft axis 25 that produces a neutral (1:0) _ .. _ .. _ _ _ _ _ _ ... = .. .. . . .
_WO 96/31715 PCIIUS96 ~ 2~89~6 -13-I,ar,~",;~_;o,~ ratio through a forward speed range from neutral (1:0) to a 1:1 I,.",~",;.,~iùn ratio, where the s~ " ' ' output (right) face 103 is normal to axis 25, and beyond into a limited overdrive speed range as indicated by the s~ h ' ' angle illustrated in Fig. 2. A first valve port 222 is connected by a fluid line 223 to the manifold port 170 that is in fluid communication withcontrol piston annular chamber 146, as seen in Fig. 2. A second valve port 224 is ~o~ e- ~d by a fluid line 225 to manifold port 180 that is in fluid communication with control piston annular chamber 148 as seen in Fig. 1.
A third valve port 226 is connected by a fluid line 227 to manifold port 192 that is in flow communication with the high pressure hydraulic fluid in sv. _ h ' cavity 196, as seen in Fig. 2. The fourth and last valve port 228 is c~""e~ d to a fluid line 229 returning to sump 230. Control valve operation is eflected by ,~ " ,9 its valve spool via operator 221 to a selected one of three valve positions indicated at 232, 234 and 236.
v'vhen ratio control valve 220 is in the valve position 234 illustrated in Fig. 6 all four valve ports are closed, allowing the fluid pressures in control piston chambers 146 and 148 to equalize. The axial position of control piston 110 is thus held steady by the balanced fluid pressures in the control chambers to set a desired lldll~lll;os;url ratio. To decrease ~Idll~lll;~sio ratio by pivoting 5 ~ ' 22 in the cou"~ l lu.h~;sa direction in Figs. 1 and 2 control valve spool is moved leftward via operator 221 to establish the valve position 236, wherein valve port 226 is fluid cu""e. ~d to valve port 224 and valve port 222 is fluid connected to valve port 228. It is thus seen that high pressure hydraulic fluid flows into annular central chamber 148 and annular control chamber 146 is vented to sump 230. The fluid pressure in chamber 148 then exceeds the fluid pressure in chamber 146 causing the volume of chamber 148 to expand as the volume of chamber 146 contracts.
Control piston 110 is thus propelled axially to the right, and s..l~l,uld~e 22 is pivoted in the COIJ~ ~Iu.k~h;3~ direction by virtue of its linkage to the 30 control piston provided by linl~ 122. vVhen the desired lower ~Idllalll;~siol~
ratio is achieved operator221 is moved rightward to ,,:e~c,Lli~l, the center WO96J31715 '2l 89846 14- rCl'lUS96/01674 valve position 234 and close off all of the valve ports. The fluid pressures in the control chambers 146 and 148 quickly equalize to set the new lower ;~ raUo.
Then to increase l, dl~alll;..SiOn ratio, valYe operator 221 is drawn to the right, such as to establish valve position 232 c~""e~Li"g valve port 226 to valve port 222 and valve port 224 to valve port 228. High pressure hydraulic fluid then flows into control chamber 146, as control chamber 148 is vented to sump 230. Control piston 110 is then propelled to the leflt, and 5~ s "hr~ ' 22 is pivoted in the clockwise direction. When the desired higher 0 1l dl la~ ;JI I ratio is achieved, the center valve position 234 is reestablished by operator 221. The fluid pressures in the control chambers 146 and 148 quickly return to balance, setting the new, higher l,d,~a",;ssion ratio.
It will be app, euid~ed that, rather than a three-position spool valve, the ratio control valve may take the form of a pair of pulse width modulated solenoid valves, such as disclosed in commonly assigned U.S. Application Serial No. 081380,269, filed January 30, 1995, the disclosure of which is i,,~,,uu, ' ' herein by reference.
From the foregoing dês-,,if,~io,), it is seen that the present invention provides an inflnitely variable ll~luald~il, lldllalll;ssiu,~ of the type disclosed in my cited: .r" " n Serial No. 08/093,192 that affords adV_.ILd9eS of compact size, fewer parts and reduced manufacturing costs. Vvhile in the preferred elllbOdi",_.ll disclosed above, the control piston 24 and control cylinder 114 are positioned in surrounding relation with pump unit 18, it will be dppl- ' '' that these elements may be positioned to surround motor unit 20. Portplate 50 and manifold block 166 would then be ,c~ ed to the output side of the motor unit in fluid communication with motor cylinders 84 through bores in the motor piston mounting bolts 75 in the manner disclosed in my cited -rr' " I Serial No. 081342,472.
~WO96/3171~ 21 89846 15- PCI/US96/01674 It will be apparent to those skilled in the art that various Illodifi.~ s and variations can be made to the apparatus of the present invention without departing from the spirit of the invention. Thus it is intended that the presentinvention cover ",~ s and variations thereof, provided they come 5 within the spirit of the appended claims and their equivalence.
RErCRE~/CE TO RELATED APPLlCATlONS
The inYention disdosed in this ~a~F" " has particular, but not ne.,~asa~ limited, ~ to the continuously vâriable l l~l us~dlk~
IldllSIll;SSiO(ls disclosed in co-pending U.S. Patent A, r~ 5~ Serial Nos.
û81093,192, filed July 13, 1993; 08/333,688, filed November 3, 1994; and 081342,472, filed November 21, 1994. The disclosures of these .~ 5 are i,,cu,~,u,d~ed herein by reference.
FIELD OF THE INVENTION
The present invention relates to hydraulic machines and, more 1û particularly, to ll~ lldl)slllii.aiulls capable of llallallli;tillg powerfrom a prime mover to a load at continuously (infinitely) variable transmission ratios.
BACKGROUND OF THE INVENTION
In my cited U.S. PatentApplication Serial No. 081093,192, a hydraulic machine is disclosed as including a hydraulic pump unit and a hydraulic motor unit positioned in opposed, axially aligned relation with an i"~. ",edi~ , wedge-shaped 5~ I,UId~ The pump unit is ..u", ,eul~d to an input shaff driven by a prime mover, while the motor unit is grounded to the stationary machine housing. An output shaff, coaxial with the input shaff and 20 drivingly coupled to a load, is pivotally conne~ d to the s~ ldld in torque coupled relation. When the pump unit is driven by the prime mover, hydraulic fluid is pumped back and forth between the pump and motor units through ports in the s~dall~ldld. As a result, three torque c~",pone"~a, all acting in the same direction, are exerted on the swdallpld~d to produce 25 output torque on the output shafl for driving the load. Two of these torque cu",pol~e"la are a Ille~,lldlliudl Cu~pol1e~1 exerted on the swaal,pldld by the rotating pump unit and a hydro-mechanical c~""~on~"l exerted on the s~,a~l,, ' ' by the motor unit. The third component is a pure ll~dlualdlic WO9613171S 2 1 8 9 846 2 - PCI~ S96101674 colllpo~ "l resulting from the ~irrcllc,,,liàl forces created by the fluid pressures acting on circu",' ~:"li. :`y opposed end surfaces of the s.._Ol,,uldl~ ports, which are of different surface areas due to the wedge shape of the sw~l ",!at,_.
To change t, d"a" ,;~ ratio, the angular ori~"' ' ~ of the sv, ~;,l ,~,l relative to the axis of the output shafl is varied. Since the l, dl lal I l;SSiOI~ ratio, i.e., speed ratio, is continuously variable, the prime mover can run at a constant speed set esse"li~ at its most efficient operating point. The y of a 1:0 (neutral) I,d"a",;~_;al~ ratio setting eliminates the need for a clutch. Unlike c~,)J~.,tional, continuously variable ~l~dlus~d~k~
~l al lal I ,issio, 15, wherein hydraulicfluid flow rate increases p, upo~ ~iu, Id~ly with increasing ~,d"a,l,;ssion ratio such that maximum flow rate occurs at the highest ~,d"a",;~aion ratio setting, the flow rate in the hydraulic machines disclosed in my cited U.S. ~rr'- " ~S reaches a maximum at a midpoint in the ratio range and then progressively decreases to esse,~ia:'y zero at the highest ~Idll~lll;.~aiUn ratio setUng. Thus, losses due to hydraulic fluid flow are reduced, and the annoying whine of conventional hydrostatic ~,d"a",;ssiol~s at high ratios is avoided. By virtue of the multiple torque c~"",ol,el"a exerted on the s~a~ll,uldL~, the de,,,~asi"~ hydraulic fluid flow in the upper half of the output speed range, and the capability of acc~"""--' ,9 an optimum perF~""a"ce prime mover input, the hydraulic machine of my cited . r' ' I has a particularly advantageous appl;~,à~io as a highly efficient, quiet, continuously variable ll~dlualdtk, ~Idrlalllissioll in vehicular drive trains.
SUMMARY OF THE INVENrlON
An objective of the present invention is to provide improvements in the ll~dlua~d~ic lldl~alllk,siull disclosed in my cited U.S. rrF' " ~ Serial No.
08/093,192, to achieve ecollor"ies in size, parts count and manufacturing cost.
An additional objective of the present invention is to provide improvements in the manner in which low pressure makeup hydraulic fluid WO 96131715 2 1 ~ 9 ~ 4 6 PCI'I~S96101674 is introduced to a I~ uald~ic ~Idl~alll;ssiol1 and the manner in which hydraulic fluid pressure iâ made available to a ratio controller on setting and changing t,d,~s",;~aiol~ ratio.
A fur~her objective of the present invention is to provide improvements 5 in a controller for setting and changing the ratio of input speed to output speed of a ll~ lUSIdli~ iull in a continuously (infinitely) variable manner.
To achieve these objectives the hydraulic machine of the present invention in its ~ as a continuously variable hydrostatic û lldllslll;ssionl CUIllp~iS~a a housing; an input shaft journaled in the housing for receiving input torque from a prime mover; an output shaft journaled in the housing for imparting driving torque to a load; a hydraulic pump unit coupled to the input shaft; a hydraulic motor unit grounded to the housing;
a wedge-shaped SWd~l luld~e: including ports extending between an input face 15 cu~r~ul'~i''g the pump unit and an output face cu,,~lu,,ti,,g the motor unit; a coupling pivotally i,,lt:, u,,,,e~i,,g the s~.&~l,r and the output shaft in torque-coupled relation; and a 1, dl IC~ io~ ratio controller including a control cylinder positioned coaxial to the output shaft in surrounding relation to one of the pump and motor units and a control piston movably mounted by the 20 control cylinder and linked to the s~asl,pldl~: such that axial movement of the control piston is converted to ll dl~a~ kn~ ratio-changing pivotal motion of the s\~&sl,uldl~ about a pivot axis of the coupling.
AddiUonal features advantages and objectives of the invention will be set forth in the des., ; , which follows and in part will be apparent from the 25 d6s~ ,ti~"~ or may be learned by practice of the invention. The objectives and advd"ld~es of the present invention will be realized and attained by the apparatus particularly pointed out in the following written des-, iution and theappended claims as well as in the accu~,t,d"~i"g drawings.
It will be ulld~ ùod that both the foregoing gene!al des- ,iulion and 30 the following detailed dea~.,i '; ~ are exemplary and ~pldl~ ~.y and are intended to provide further e~pld,,dliùl~ of the invention as claimed.
WO 96/3171~ PCIIUS96/01674 2t8~846 -4-The a~ ul~lpd~ lg drawings are intended to provide a further ul~ ldll.lillg of the invention and are illuul,u~ldlt:d in and constitute a partof the ~Fe~ , illustrate a preferred embodiment of the invention and, together with the des~d i,u~iùl~, serve to explain the principles of the invention.
BRIEF DE:~Cfib I ION OF rHE DRAWINGS
Fig. 1 is a longitudinal secUonal view of a continuously variable lldllalll;~ structured in acc~"~ance with a preferred embodiment of the present invention;
Fig. 2 is an enlarged r,dy",~"ld~y, longitudinal sectional view of the 1û input end portion of the lldll~lll;ssiûl~ of Fig. 1 that ill~rf.u, ' ~ different sectional views of a manifold block.
Figs. 3 and 4 are plan views of opposed faces of a portplate seen in Figs. 1 and 2.
Fig. S is a plan view of one face of a manifold block seen in Figs. 1 and 2.
Fig. 6 is a schematic view of an external lldll:,lll;ssiol1 ratio control valve uUlized with the ll~dlu~dlic lldll~lll;~aiol1 of Figs. 1 and 2.
C~ ,uoll.li,ly reference numerals refer to like parts throughout the several views of the drawings.
DETAILED DtSÇP~" IIQN OF THE PREI L~RELI EMBODlMENr The continuously variable ll~llualdliu lldll~ iol~ according to the preferred ~Illbodi~ l of the present invention, generally indicated at 10 in Ule overall view of Fig. 1, comprises, as basic c~",uol~"l~, a housing 12 in which are journaled an input shan 14 and an output shan 16 in coaxial, generally end-to-end relation. The end of input shan 14 external to the housing is splined, as indicated at 14a, to facilitate driving col~l~eu~iùn tû aprime mover (not shown), while the end of output shan 16 external to the housing is splined, as indicated at 16a, to facilitate driving C~ u~iOIl to a load (not shown). Input shan 14 drives a hydraulic pump unit, generally indicated at 18. A hydraulic motor unit, generally indicated at 20, is grounded to housing 12 in axially opposed relation to pump unit 18. A
~WO96/31715 2 1 ~d q P~ 4 6 5 ~ 674 wedge-shaped s\._~h, ' ', generally indicated at 22, is drivingly uu""el,Led to the output shaft 16 in a position between the pump and motor units and is apertured, one aperture indicated at 23, to ac~,u"""odd~e e~.,l,allges of hydraulic fluid between the pump and motor units. A control piston 24 is 5 linked to s~. ~,u'_'~ 22 for the purpose of pivotally adjusting the angle of SWd~l 1, ' ' O(iél 1' " ~ relatiYe to the output shaft axis 25, thereby adjustably setting the ~ldllalllis~siol~ ratio of the input shaft speed to the output shaftspeed.
Now referring jointly to Figs. 1 and 2 in greater detail, the cylindrical 1û housing 12 includes a cover 30 secured in place by an annular array of bolts, one seen at 31, to close off the open input end of the housing. Input shaft 14 extends into housing 12 through central openings in the cover and a manifold assembly, generally indicated at 34, that is secured in place between the cover and housing by the bolts 31. Bearings 35, fitted in the 15 cover and manifold assembly openings, joumal the input shafl 14 for rotation. An annular end cap 36, afffixed to cover 30 by bolts 37, holds a seal 38 against the input shaft peripheral surface to prevent leakage of hydraulic fluid.
As best seen in Fig. 2, the inner end of input shaft 14 is counterbored 20 to provide a cylindrical recess 40 for receiving a reduced diameter inner terminal pûrtion 42 of output shafl 16. A roller bearing ring 44, fitted in recess 40, provides inner end joumal support for the output shaft. The inner terminal portion of input shaft 14 beyond a hub member 45 of manifold assembly 34 is flared to provide a radial flange 47 having a splined 25 peripheral surface in meshed e"~ag~"~e"l with a splined central bore ~commonly indicated at 48) of an annular thrust washer 49. An annular portplate 50 is positioned between manifold assembly 34 and thrust washer 49.
The right radial face of thrust washer 49 is recessed to receive the 3û radially fiared left end portion of a carrier 56 for a plurality of pistons included in hydraulic pump unit 18. These pistons, for example, ten in number with . _ _ _ _ . _ . . . .
WO 96/31715 ~ .'OIC74 one being generally indicated at 58, are uniformly distributed in a circular array cu~)c~ iu with output shaft axis 25 in the manner disclosed in my dted patent ~,~, ' " ns. As illustrated in Fig. 2 herein, each pump piston 58 includes a piston head 6û mounted to the piston carrier 56 by an 5 elongated bolt 61 extending through a hole in the piston carrier and threaded into a tapped hole in thrust washer 49, as indicated at 49a. Piston head 6û
is machined to provide a spherical inner surface cc,,,tu,,,,i,,g to a spherical outer surface of an annular bearing 62 keyed on a bushing 63 carried by bolt 61. A standoff sleeve 64 is also carried on bolt 61 such that, when th-~ bolt 1û is tightened down, bushing 63 is clamped in place to app,u~i.,t~,ly pc~sitionbearing 62 and piston head 6û in axially spaced relation to piston carrier 56.
As a result, each piston head 60 is mounted for limited radial and swivel motions.
The cylindrical right end portion of pump piston carrier 56 carries an 15 annular spherical bearing 66 . ur,fu, " ,i"~ to a spherical surface 67 machined in the central opening of an annular pump cylinder block 68. An annular uu~ ul tlaaion spring 69 acting against axlally opposed shoulders provided on carrier 56 and spherical bearing 66 urge the spherical bearing rightward toward the output end of lldllalll;~a;ûn. A roller bearing ring 70 is confined 20 in the central opening of pump piston carrier 56, through which output shaft 16 extends, to provide joumal support for pump piston carrier 56. Cylinder block 68 Includes an annular array of pump cylinders 72 for ,~st,e.,lh~cly receiving the pump pistons 58. By virtue of the spherical bearing mountings of pump piston heads 60 and pump cylinder block 68"~, ~aail ,~ motion of 25 the pump cylinder block axis relatlve to output shaft axls 25 is accullllll~
Retuming tû Fig. 1, hydraulic motor unit 20 is ess~,.ti~.l'y structurally equivalent to hydraulic pump unlt 18. However, an annular motor piston carrier 74, equivalent to rotating pump piston carrier 56, is instead grounded 30 to housing 12 by an annular array of bolts 75. These bolts also serve to mount motor pistons, generally indicated at 76, each including a piston head WO 96131715 PCI'IUS96/01674 ~ 7 ~
21 8~46 77 swivel mounted on a spherical bearing 78 positioned in standoff relation to pump piston carrier 74 by a sleeve 79 in the same manner as pump pistons 58. A motor cylinder block 80 is then swivel mounted on carrier 74 via an annular spherical bearing 82. An annular co~ saoiol~ spring 83 urges spherical bearing 82 leftward toward the input end of 1, dl ,a",;o,~;~n 10.
Again, as in the case of pump cylinder block 68, a circuiar array of motor cylinders 84 are formed in cylinder block 80 to ~t:Opeuth~,ly receive motor pistons 76. Since motor unit 20 is grounded to housing 12 by bolts 75, the motor pistons 76 and cylinder block 80 do not rotate, however, the spherical bearing mountings of motor piston heads 77 to bolts 75 and motor cylinder block 80 to carrier 74 aCC~IIIIIIOdd~ nutating (~ aaillg) motion of the motor cylinder block axis.
As further seen in Fig. 1, output shaft 16 extends rightward through the central opening in motor piston carrier 74, where a supporting roller bearing ring 85 is positioned, and out of housing 12 through a central opening in a hub-shaped output end closure 86 affxed to housing 12 by bolts, one seen at 87. A roller bearing ring 89, positioned in the end closure central opening provide further journal support for the output shaft. An annular end cap 92, affixed to end closure 86 by bolts 93, confines a seal 94 against the surface of output shaft 16 at the point of final exit from the housing to prevent leakage of hydraulic fluid.
S~&ol, ' 22 is drivingly connected to output shaft 16 in operative position between pump unit 18 and motor unit 20 by transverse pins 96 (~ape~ received in did",~ ,a:'; opposed hubs 98 affixed to the output shaft. The common axis of pins 96~ ~, II "~go"al to the output shaf axis 25~
constitutes a pivot axls for S\li~dallp~ 22 to accommodate l~dna~l; ,sion ratio-change adjustment of the sv~dal Ir l ' angular ~, i~, l 'i~ n relative to the output shaf axis 25.
Returning to Fig. 2~ 5Wdoll,' ' 22 includes an input face 101 in intimate sliding contact with face 102 of pump cylinder block 68 and an output face 103 in intimate sliding contact with face 104 of motor cylinder WO 96131715 rCr/US96101674 21 8~846 -8-block 80. The input and output faces of sw~sl~, 22 are relatively oriented at an acute angle to proYide the wedged shape of the swdal,, Ports 23 extend between the input and output faces o~ the s~. h~ and communicate with respectiYe openings 107 into cylinders 72 of pump cylinder block 68 and respectiYe openings 108 into the cylinders 84 in motor cylinder block 80, all as more fully described and illustrated in my cited patent ~ ,~ 1S.
Ratio control piston 24 comprises a rightward cylindrical section 110 and a leffward cylindrical section 112 that are joined ess~"t;~:'y end to end by screw threads 113. The ratio control piston 24 is slidingly mounted on a control cylinder 114 that is proYided with a pair of didllle:tlica:!y opposed v~a,d'y extending ears 116 haYing apertures through which the 11, piYot pins 96 extend. The output end of piston section 110 is fommed with a pair of closely, angularly spaced tangs 118 that are apertured to mount the ends of a pin 120, which, in turn, piYotally mounts one end of a link 122 positioned between tangs 118 in closely spaced relation. The other end of link 122 is piYotally connected to a pin 124 that is carried by a pair of closely, angularly spaced tangs 126 in flanking relation to the link.
Tangs 126 are radially outward pluj~. tiUI la of a connector block 128 that is fitted in a recess 129 formed in S~dalllJId~ 22 and held in place by a transverse locking pin 130.
It is thus seen that axially, t~ ., Ul,d~il Iy movement of control piston 24 is translated into angular motion of the swaallpld~ as it piYots about its piYotal cc ""e~ (pins 96) to output shaff 16. It is also seen that, by Yirtue 25 of this c,nneliu" and the c~""e. tiOI1 of control cylinder ears 116 to the s~v~ ,u'..'~ pivot pins 96, control piston 24 and control cylinder 114 rotate in unison with output shaff 16. A free end segment 110a of control piston section 110 is machined to proYide an annularly distributed balancing mass for the purpose of co~", Lald~".i"g the eccentric masses of the s\. a~l Ipld~:
22, and the ,u, t:l eaaillg pump cylinder block 68 and motor cylinder block 80 as fully explained in my U.S. patent .~, 'ic.~ Serial No. 08/093,192.
.. _ . .. . . .. . . . . . .. . . . . . . .
Still refening to the enlarged view of Fig. 2, the lefl end of control cylinder 114 is fommed with a radially inwardly extending lip 132 that serves as an axial stop to engage portplate 50 ass6",bled within the control cylinder in a press-fit manner. A clamping ring 134, having a threaded periphery engaging an intemal threaded section 135 of control cylinder 114, is turned down to securely clamp portplate 50 against lip 132. Thus, annular portplate 50 also rotates in unison with output shaft 16.
The leflt end of control piston section 112 is machined to proYide an annular shoulder 140 that projects radially inward into sliding ell~dge",e"l with the peripheral surface of control cylinder 114. The control cylinder is machined to provide an annular shoulder 142 projecting radially outward into sliding el~gag~",t:"I with an inner cylindrical surface of control piston section 112. The space between control piston section 112 and control cylinder 114 that is axially defined by the opposed shoulders 140 and 142 provides an annular control chamber 146. Another annular control chamber 148 is provided by the radial spacing between the control cylinder and control piston section 112 that is axially defined by shoulder 142 and the input (lefl) end surface 149 of piston section 110. Seal rings 150 are i"c~l~,o,aled in shoulders 140 and 142 and piston section 110 to prevent hydraulic fluid leakage from chambers 146 and 148.
At angularly spaced locations, longitudinal bores are drilled into the left end of control cylinder 114 to provide fluid passages 152 (Fig. 1) and 154 (Fig. 2). Passage 152 1e~ alc:5 in a radial passage 153 to the output ~right) side of shoulder 142 and thus opens into chamber 148. Shorter passage 154 k"",;"ales in a radial passage 155 on the left (input) side of shoulder 142 and thus opens into chamber 146. The outer ends of passages 152 and 154 are plugged, as indicated at 156 in Fig. 2. As seen in Fig. 2, passage 154 communicates with a radial passage 158 drilled in portplate 50 via a short connector passage 159 drilled in control cylinder 114. Theinnerendofradialpassage158communicateswithalongitudinal passage 160 that, in tum, communicates with a shallow annular cavity 162 WO 96/31715 2 ~ 8 9 8 4 6 - 10 - PCIJUS96101674 formed in the input radial face 163 of portplate 50, as also seen in Fig. 3.
At a radius equal to that of cavity 162, a longitudinal passage 164 is drilled into an annular manifold block 166 press-fitted on hub 45 of manifold assembly 34. The left end of longitudinal passage 164 opens into a radial passage 168, whose outer end t~llllilld~:s at a port 170 in manifold block 166.
In the same manner and as illustrated in Fig. 1, longitudinal passage 152 in control cylinder 114 communicates with a radial passage 172, drilled in portplate 50, via a short connector passage 173 in control cylinde~ 114.
The inner end of radial passage 172 communicates with a longi~udinal passage 174 that opens into a shallow annular cavity 175 machined in the input radial face 163 of portplate 50 (Fig. 3). A longitudinal passage 177 is drilled into the right face of manifold block 166 at a radius equal to that of cavity 175. The inner end of passage 177 opens into a radial passage 178, whose outer end l~ illdl~s at a port 180 in the manifold block.
It is seen that, although portplate 50 rotates with the output shaff and man'lfold block 166 is grounded to housing 12 by bolts 31, the annular caviUes 162 and 175 in the portplate provide continuous fluid communication between the longitudinal passage 160 and 164 and between longitudinal passages 174 and 177, le:!3dlU~ of the angular relation of the rotating portplate and stationary manifold block. Thus, during 1, dl 1:~11 I;SSiOI) operation, port 170 is in continuous fluid communication with chamber 146, and port 180 is in continuous fluid communication with chamber 148.
To ensure an adequate supply of makeup hydraulic fluid from a sump pump 182, three additional ports are formed in manifold block 166 at 1200 angularly spaced positions. One of these makeup ports is iliustrated in Fig.
1 at 184. Each makeup port communicates with a radial passage 186 drilled in manifold block 166, which, in turn, communicates with an angular passage 188 that opens into the right radial face of the manifold block in c~l,r,~ 9 relation with an outermost semi-annular cavity 190 machined into the left radial face 163 of portplate 50, as seen in Fig. 3. A final manifold port 192, ~WO 96/31715 ~ 1 8 ~ 8 4 6 1 1 - PCr/US96/01674 seen in Fig. 2, communicates with a radial passage 193 in manifold block 166, which, in turn, communicates with a longitudinal passage 194 that opens into the right radial face o~ the manifold block in cu~rlul ," ,9 relationwith an annular cavity 196 machined in portplate face 163 (Fig. 3).
The relative angular and radial ~osiliol,i"~s of the manifold passages at the right radial face 199 of manifold block 166 are illustrated in Fig. 5. It is pointed out that the sections of manifold block 166, portplate 5û and control cylinder 114 illustrated in Figs. 1 and 2 have been chosen to best illustrate the hydraulic fluid flow l~ldliUI~ ,s of the various passages 1û therein, and thus do not represent their actual angular I~I'ioll~ll;ys, which, in the case of manifold block 166, can be seen in Fig. 5.
The right radial face 2ûû ûf portplate 5û, seen in plan view in Fig. 4, is machined to proYide a pair of didll~ y opposed, semi-annular (kidney-shaped) surface r~avities 202 and 204. A pair of kidney-shaped ports 206 proYide fluid communication between cavities 190 and 202 through portplate 50, while a pair of kidney-shaped ports 208 provide fluid communication between cavities 204 and 196, as also seen in Fig. 3.
Returning to Fig. 2, the pump piston mûunting bolts 61 are drilled with axial bores 210 (illustrated in phantom line), such that the fluid pressures in the pump cylinders 72 are communicated to separate recesses 212 formed in the lefl radial face of thrust washer 49 bearing against the right face 200 (Fig. 4) of portplate 50. Thus, the pump cylinder fluid pressures are communicated to surface cavities 202 and 204 in portplate face 200 and then to surface cavities 190 and 196 in portplate face 163 (Fig. 3) via ports 206 and 208.
When the pump pistons 58 and pump cylinders 72 revolve from the thinnest point of the wedge-shaped s~ l Ipldle: 22 around to its did" lell i.,.. 'y opposed thickest point, the volumes ûf the ~,o~ ' ?d pump cylinders ~I~Jylt7a~ cly decrease, and the hydraulic fluid in these pump cylinders is 30 therefore being pressurized. This is cùl~sid~ d to be the high pressure or pumping side of hydraulic pump unit 18.
WO 96131715 ~ .'OIC74 '21 8q846 12-Vvhen, the pump pistons and pump cyiinders revolve from the thickest point around to the thinnest point of the s~c~l,, ' ' 22, the volumes of the ~s ~ ' ' pump cylinders 72 are progressively expanded. This is sicl~ d to be the low pressure or suction side of the hydraulic pump unit 5 18.
Since portplate 50 and s~v;.~l Ir ' ' 22 rotate in unison, because both are Ued to output shaft 1 6, the angular, ~ t~ollsl ,ips of the portplate surface cavities to the high pcessure (pumping) and low pressure ~suction) sides of pump unit 18, as dt,l~""i"ed by the S~ Jldl~, remain fixed 1~9dl~ldaS of 10 input to output shaft speed ratio. The angular o~i~"' " ~ of portplate 50 relative to the sv/asl)pldL~: is such that the hydraulic fluid in portplate surface caviUes 190 and 206, introduced from by the sump pump 182 through manifold block ports 184 and passages 186, 188, assumes the average fluid pressure in the pump cylinders 72 involved in the suction side of pump unit 18 by virtue of the fluidic c~llllel,Lio,~a provided by bores 210 in the pump piston mounting bolts 61. The provision of three makeup passages 188 spaced 120 apart guarantees that at least two makeup ports are always in fluid communication with the 180 arcuate surface cavity 190 in the leflt radialface 163 of portplate 50 (Fig. 3). Consequently, starvation of hydraulic fluid 20 in pump unit 18 is prevented.
On the other hand, hydraulic fluid that has filled portplate surface cavities 196 and 204 through the bores 210 in the pump piston mounting bolts 61, is pressurized to an average of the fluid pressures in the pump cylinders 72 invoived in the high pressure (pumping) side of pump unit 18.
25 As described above, the high pressure hydraulic fluid in portplate cavity 196is in flow communication with port 192 through manifold passages 193 and 194.
A ratio control valve 220, such as illustrated in Fig. 6, is provided to stroke (change) tldlla",;i,aiLn 10 through a limited reverse speed range of 30 acute s~ ,;,p'..`~ angles COUIIL~ILIOCk~ of a S.Vr hr~ ' input (lefl) face 101 angle normal to the output shaft axis 25 that produces a neutral (1:0) _ .. _ .. _ _ _ _ _ _ ... = .. .. . . .
_WO 96/31715 PCIIUS96 ~ 2~89~6 -13-I,ar,~",;~_;o,~ ratio through a forward speed range from neutral (1:0) to a 1:1 I,.",~",;.,~iùn ratio, where the s~ " ' ' output (right) face 103 is normal to axis 25, and beyond into a limited overdrive speed range as indicated by the s~ h ' ' angle illustrated in Fig. 2. A first valve port 222 is connected by a fluid line 223 to the manifold port 170 that is in fluid communication withcontrol piston annular chamber 146, as seen in Fig. 2. A second valve port 224 is ~o~ e- ~d by a fluid line 225 to manifold port 180 that is in fluid communication with control piston annular chamber 148 as seen in Fig. 1.
A third valve port 226 is connected by a fluid line 227 to manifold port 192 that is in flow communication with the high pressure hydraulic fluid in sv. _ h ' cavity 196, as seen in Fig. 2. The fourth and last valve port 228 is c~""e~ d to a fluid line 229 returning to sump 230. Control valve operation is eflected by ,~ " ,9 its valve spool via operator 221 to a selected one of three valve positions indicated at 232, 234 and 236.
v'vhen ratio control valve 220 is in the valve position 234 illustrated in Fig. 6 all four valve ports are closed, allowing the fluid pressures in control piston chambers 146 and 148 to equalize. The axial position of control piston 110 is thus held steady by the balanced fluid pressures in the control chambers to set a desired lldll~lll;os;url ratio. To decrease ~Idll~lll;~sio ratio by pivoting 5 ~ ' 22 in the cou"~ l lu.h~;sa direction in Figs. 1 and 2 control valve spool is moved leftward via operator 221 to establish the valve position 236, wherein valve port 226 is fluid cu""e. ~d to valve port 224 and valve port 222 is fluid connected to valve port 228. It is thus seen that high pressure hydraulic fluid flows into annular central chamber 148 and annular control chamber 146 is vented to sump 230. The fluid pressure in chamber 148 then exceeds the fluid pressure in chamber 146 causing the volume of chamber 148 to expand as the volume of chamber 146 contracts.
Control piston 110 is thus propelled axially to the right, and s..l~l,uld~e 22 is pivoted in the COIJ~ ~Iu.k~h;3~ direction by virtue of its linkage to the 30 control piston provided by linl~ 122. vVhen the desired lower ~Idllalll;~siol~
ratio is achieved operator221 is moved rightward to ,,:e~c,Lli~l, the center WO96J31715 '2l 89846 14- rCl'lUS96/01674 valve position 234 and close off all of the valve ports. The fluid pressures in the control chambers 146 and 148 quickly equalize to set the new lower ;~ raUo.
Then to increase l, dl~alll;..SiOn ratio, valYe operator 221 is drawn to the right, such as to establish valve position 232 c~""e~Li"g valve port 226 to valve port 222 and valve port 224 to valve port 228. High pressure hydraulic fluid then flows into control chamber 146, as control chamber 148 is vented to sump 230. Control piston 110 is then propelled to the leflt, and 5~ s "hr~ ' 22 is pivoted in the clockwise direction. When the desired higher 0 1l dl la~ ;JI I ratio is achieved, the center valve position 234 is reestablished by operator 221. The fluid pressures in the control chambers 146 and 148 quickly return to balance, setting the new, higher l,d,~a",;ssion ratio.
It will be app, euid~ed that, rather than a three-position spool valve, the ratio control valve may take the form of a pair of pulse width modulated solenoid valves, such as disclosed in commonly assigned U.S. Application Serial No. 081380,269, filed January 30, 1995, the disclosure of which is i,,~,,uu, ' ' herein by reference.
From the foregoing dês-,,if,~io,), it is seen that the present invention provides an inflnitely variable ll~luald~il, lldllalll;ssiu,~ of the type disclosed in my cited: .r" " n Serial No. 08/093,192 that affords adV_.ILd9eS of compact size, fewer parts and reduced manufacturing costs. Vvhile in the preferred elllbOdi",_.ll disclosed above, the control piston 24 and control cylinder 114 are positioned in surrounding relation with pump unit 18, it will be dppl- ' '' that these elements may be positioned to surround motor unit 20. Portplate 50 and manifold block 166 would then be ,c~ ed to the output side of the motor unit in fluid communication with motor cylinders 84 through bores in the motor piston mounting bolts 75 in the manner disclosed in my cited -rr' " I Serial No. 081342,472.
~WO96/3171~ 21 89846 15- PCI/US96/01674 It will be apparent to those skilled in the art that various Illodifi.~ s and variations can be made to the apparatus of the present invention without departing from the spirit of the invention. Thus it is intended that the presentinvention cover ",~ s and variations thereof, provided they come 5 within the spirit of the appended claims and their equivalence.
Claims (24)
1. A continuously variable hydrostatic transmission comprising:
a housing;
an input shaft journaled in the housing for receiving input torque from a prime mover;
an output shaft journaled in the housing for imparting output torque to a load;
a hydraulic pump unit drivingly coupled to the input shaft;
a hydraulic motor unit grounded to the housing;
a wedge-shaped swashplate operatively positioned between the hydraulic pump and motor units and including ports accommodating hydraulic fluid transfers between the hydraulic pump and motor units, a coupling pivotally connecting the swashplate to the output shaft in torque-coupled relation; and a transmission ratio controller including:
a control cylinder positioned coaxial to the output shaft axis in surrounding relation to one of the hydraulic pump and motor units, and a cylindrical control piston movably mounted by the control cylinder and linked to the swashplate such that axial movement of the control piston is converted to transmission ratio-changing pivotal motion of the swashplate about a pivot axis of the coupling.
a housing;
an input shaft journaled in the housing for receiving input torque from a prime mover;
an output shaft journaled in the housing for imparting output torque to a load;
a hydraulic pump unit drivingly coupled to the input shaft;
a hydraulic motor unit grounded to the housing;
a wedge-shaped swashplate operatively positioned between the hydraulic pump and motor units and including ports accommodating hydraulic fluid transfers between the hydraulic pump and motor units, a coupling pivotally connecting the swashplate to the output shaft in torque-coupled relation; and a transmission ratio controller including:
a control cylinder positioned coaxial to the output shaft axis in surrounding relation to one of the hydraulic pump and motor units, and a cylindrical control piston movably mounted by the control cylinder and linked to the swashplate such that axial movement of the control piston is converted to transmission ratio-changing pivotal motion of the swashplate about a pivot axis of the coupling.
2. The continuously variable hydrostatic transmission defined in claim 1, wherein the ratio controller further includes first and second annular control chambers defined between the control cylinder and the control piston, such that hydraulic fluid pressure differentials in the first and second controlchambers produce the axial movement of the control piston.
3 The continuously variable hydrostatic transmission defined in claim 2, wherein the first and second control chambers are defined by radially and axially opposed surface portions of the control cylinder and control piston.
4. The continuously variable hydrostatic transmission defined in claim 3, wherein the control cylinder is connected to the coupling in fixed axial position while rotating in unison with the control piston, swashplate and output shaft.
5. The continuously variable hydrostatic transmission defined in claim 4, wherein the ratio controller further includes a control valve in fluid communication with the first and second chambers and selectively operable to create any one of the following conditions, 1) a hydraulic fluid pressure balance in the first and second control chambers to set an angular position of the swashplate to a desired transmission ratio, 2) a greater hydraulic fluid pressure in the first control chamber than in the second control chamber to pivot the swashplate about the pivot axis in a transmission ratio-increasing direction, and 3) a greater hydraulic fluid pressure in the second control chamber than in the first control chamber to pivot the swashplate about the pivot axis in a transmission ratio-decreasing direction.
6. The continuously variable hydrostatic transmission defined in claim 5, further including a link pivotally connecting a free end of the controlpiston to the swashplate at a location radially offset from the pivot axis.
7. The continuously variable hydrostatic transmission defined in claim 5, wherein the ratio controller further includes a hydraulic fluid circuitconnecting the control valve to a source of pressurized hydraulic fluid in one of the hydraulic pump and motor units.
8. The continuously variable hydrostatic transmission defined in claim 5, further comprising:
an annular portplate coupled to rotate in unison with the output shaft and including fluid passages; and a manifold fixed to the housing and including fluid passages communicating with the portplate fluid passages, the portplate and manifold fluid passages arranged to provide separate hydraulic fluid circuit connections between the control valve and each of the first control chamber, the second control chamber, and a source of pressurized hydraulic fluid in one of the hydraulic pump and motor units.
an annular portplate coupled to rotate in unison with the output shaft and including fluid passages; and a manifold fixed to the housing and including fluid passages communicating with the portplate fluid passages, the portplate and manifold fluid passages arranged to provide separate hydraulic fluid circuit connections between the control valve and each of the first control chamber, the second control chamber, and a source of pressurized hydraulic fluid in one of the hydraulic pump and motor units.
9. The continuously variable hydrostatic transmission defined in claim 5, further comprising:
an annular portplate coupled to rotate in unison with the output shaft, the portplate including 1) a radial face having first and second radiallyoffset, annular cavities therein, 2) a first fluid passage providing fluid communication between the first control chamber and the first annular cavity, and 3) a second fluid passage providing fluid communication between the second control chamber and the second annular cavity; and a manifold fixed to the housing, the manifold including 1) a radial face in sliding interfacial engagement with the portplate radial face, 2) first and second ports connected to the control valve by separate fluid lines, 3) a first fluid passage leading from the first port to a first opening in the manifold radial face aligned with the first annular cavity, and 4) a second fluid passage leading from the second port to a second opening in the manifold radial face aligned with the second annular cavity.
an annular portplate coupled to rotate in unison with the output shaft, the portplate including 1) a radial face having first and second radiallyoffset, annular cavities therein, 2) a first fluid passage providing fluid communication between the first control chamber and the first annular cavity, and 3) a second fluid passage providing fluid communication between the second control chamber and the second annular cavity; and a manifold fixed to the housing, the manifold including 1) a radial face in sliding interfacial engagement with the portplate radial face, 2) first and second ports connected to the control valve by separate fluid lines, 3) a first fluid passage leading from the first port to a first opening in the manifold radial face aligned with the first annular cavity, and 4) a second fluid passage leading from the second port to a second opening in the manifold radial face aligned with the second annular cavity.
10. The continuously variable hydrostatic transmission defined in claim 9, wherein the portplate radial face further includes a third annular cavity radially offset from the first and second cavities and in fluid communication with a source of pressurized hydraulic fluid in one of the hydraulic pump and motor units, and the manifold further includes 1) a third port connected to the control valve by a fluid line, and 2) a third fluid passage leading from the third port to a third opening in the manifold radial face aligned with the third annular cavity.
11. The continuously variable hydrostatic transmission defined in claim 10, wherein the portplate radial face further includes a fourth cavity radially offset form the first, second and third cavities, the fourth cavity in fluid communication with the one of the hydraulic pump and motor units, and the manifold further includes 1) a fourth port connected to a source of makeup hydraulic fluid, and 2) a fourth fluid passage leading from the fourth port to a fourth opening in the manifold radial face positioned for fluid communication with the fourth cavity.
12. The continuously variable hydrostatic transmission defined in claim 11, wherein the third cavity is in fluid communication with a high pressure side of the hydraulic pump unit, and the fourth cavity is in fluid communication with a low pressure side of the hydraulic pump unit.
13. The continuously variable hydrostatic transmission defined in claim 12, wherein the hydraulic pump unit includes:
a cylinder block defining a circle array of pump cylinders, a carrier drivingly coupled to the input shaft, a plurality of pump pistons, each mounted to the carrier by a mount in a position slidingly received in a different one of the pump cylinders, the mounts having axial bores providing the fluid communication between the third cavity and those of the pump cylinders revolving in the high pressure side of the hydraulic pump and the fluid communication between the fourth cavity and those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit.
a cylinder block defining a circle array of pump cylinders, a carrier drivingly coupled to the input shaft, a plurality of pump pistons, each mounted to the carrier by a mount in a position slidingly received in a different one of the pump cylinders, the mounts having axial bores providing the fluid communication between the third cavity and those of the pump cylinders revolving in the high pressure side of the hydraulic pump and the fluid communication between the fourth cavity and those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit.
14. The continuously variable hydrostatic transmission defined in claim 13, wherein the first, second, third, and fourth cavities are formed in a first radial face of the portplate, the portplate further including:
a second radial face opposite the first radial face, a fifth semi-annular cavity formed in the second radial face, a first plurality of the mount bores providing fluid communication between the fifth cavity and those of the pump cylinders revolving in the high pressure side of the hydraulic pump unit, a sixth semi-annular cavity formed in the second radial face in diametrically opposed relation to the fifth cavity, a second plurality of the mount bores providing fluid communication between the sixth cavity and those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit, a first axial port providing fluid communication between the third and fifth cavities, and a second axial port radially offset from the first axial port and providing fluid communication between the fourth and sixth cavities.
a second radial face opposite the first radial face, a fifth semi-annular cavity formed in the second radial face, a first plurality of the mount bores providing fluid communication between the fifth cavity and those of the pump cylinders revolving in the high pressure side of the hydraulic pump unit, a sixth semi-annular cavity formed in the second radial face in diametrically opposed relation to the fifth cavity, a second plurality of the mount bores providing fluid communication between the sixth cavity and those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit, a first axial port providing fluid communication between the third and fifth cavities, and a second axial port radially offset from the first axial port and providing fluid communication between the fourth and sixth cavities.
15. A continuously variable hydrostatic transmission comprising:
a housing;
an input shaft journaled in the housing;
an output shaft journaled in the housing and having an axis;
a hydraulic pump unit including:
a carrier drivingly coupled for rotation by the input shaft;
a plurality of pump pistons mounted to the carrier in a circle array by respective mounts having through-holes, and a cylinder block defining a circle array of pump cylinders in which the pump pistons are respectively, slidingly received;
a hydraulic motor unit including:
a carrier grounded to the housing, a plurality of motor pistons mounted to the carrier in a circle array, and a cylinder block defining a circle array of motor cylinders in which the motor pistons are respectively, slidingly received;
a wedge-shaped swashplate drivingly, pivotally connected to the output shaft in an operative position between the hydraulic pump and motor units and including ports accommodating pumping exchanges of hydraulic fluid between the pump and motor cylinders, the swashplate defining diametrically opposed high and low pressure sides of the hydraulic pump unit through which the pump cylinders revolve;
a controller coupled to adjust an angular orientation of the swashplate relative to the output shaft axis, thereby varying a transmission ratio of input to output shaft speed;
a manifold fixed to the housing, the manifold including:
a radial face, and a plurality of first internal fluid passages terminating at a correspondingly plurality of angularly spaced, first openings in the radial faceat equal radius position;
a portplate positioned between the manifold and the pump piston carrier and coupled to rotate in unison with the output shaft, the portplate including:
a first radial face in interfacial sliding engagement with the manifold radial face, a semi-annular first cavity formed in the first radial face at a radius position corresponding to the radius positions of the first openings, such that, during rotation of the portplate relative to the manifold, fluid communication is maintained between the first cavity and at least one of the first openings, a second radial face opposite the first radial face, an arcuate second cavity formed in the second radial face at an angular position in fluid communication with those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit via the pump piston mount through-holes, and a first axial port providing fluid communication between the first and second cavities; and a sump pump connected to the first internal passages to supply makeup hydraulic fluid to the pump cylinders revolving in the low pressure side of the hydraulic pump unit.
a housing;
an input shaft journaled in the housing;
an output shaft journaled in the housing and having an axis;
a hydraulic pump unit including:
a carrier drivingly coupled for rotation by the input shaft;
a plurality of pump pistons mounted to the carrier in a circle array by respective mounts having through-holes, and a cylinder block defining a circle array of pump cylinders in which the pump pistons are respectively, slidingly received;
a hydraulic motor unit including:
a carrier grounded to the housing, a plurality of motor pistons mounted to the carrier in a circle array, and a cylinder block defining a circle array of motor cylinders in which the motor pistons are respectively, slidingly received;
a wedge-shaped swashplate drivingly, pivotally connected to the output shaft in an operative position between the hydraulic pump and motor units and including ports accommodating pumping exchanges of hydraulic fluid between the pump and motor cylinders, the swashplate defining diametrically opposed high and low pressure sides of the hydraulic pump unit through which the pump cylinders revolve;
a controller coupled to adjust an angular orientation of the swashplate relative to the output shaft axis, thereby varying a transmission ratio of input to output shaft speed;
a manifold fixed to the housing, the manifold including:
a radial face, and a plurality of first internal fluid passages terminating at a correspondingly plurality of angularly spaced, first openings in the radial faceat equal radius position;
a portplate positioned between the manifold and the pump piston carrier and coupled to rotate in unison with the output shaft, the portplate including:
a first radial face in interfacial sliding engagement with the manifold radial face, a semi-annular first cavity formed in the first radial face at a radius position corresponding to the radius positions of the first openings, such that, during rotation of the portplate relative to the manifold, fluid communication is maintained between the first cavity and at least one of the first openings, a second radial face opposite the first radial face, an arcuate second cavity formed in the second radial face at an angular position in fluid communication with those of the pump cylinders revolving in the low pressure side of the hydraulic pump unit via the pump piston mount through-holes, and a first axial port providing fluid communication between the first and second cavities; and a sump pump connected to the first internal passages to supply makeup hydraulic fluid to the pump cylinders revolving in the low pressure side of the hydraulic pump unit.
16. The continuously variable hydrostatic transmission defined in claim 15, wherein the manifold includes at least three first openings relativelyangularly spaced such that makeup fluid communication is maintained between the first cavity and at least two of the first openings during rotation of the portplate relative to the manifold.
17. The continuously variable hydrostatic transmission defined in claim 15, wherein the manifold further includes at least one first peripheral port for connecting the sump pump to the first fluid passages.
18. The continuously variable hydrostatic transmission defined in claim 17, wherein the manifold further includes 1) a second peripheral port and 2) a second internal fluid passage leading from the second peripheral port to a second opening in the manifold radial face at a position radially offset form the first opening radius positions, and the portplate further includes 1) annular third cavity formed in the first radial face at a position in continuous fluid communication with the second opening, 2) an arcuate fourth cavity formed in the second radial face at a position in diametrically opposed relation to the second cavity and in fluid communication with those of the pump cylinders revolving in the high pressure side of the hydraulic pump unit via the pump piston mount through-holes, and 3) a second axial port providing fluid communication between the third and fourth cavities.
19. The continuously variable hydrostatic transmission defined in claim 18, wherein the transmission ratio controller includes:
a control cylinder positioned coaxial to the output shaft axis in surrounding relation to the hydraulic pump unit, and a cylindrical control piston movably mounted by the control cylinder and linked to the swashplate, such that axial movement of the control piston is converted to transmission ratio-changing pivotal motion of the swashplate about a pivot axis intersecting the output shaft axis in orthogonal relation.
a control cylinder positioned coaxial to the output shaft axis in surrounding relation to the hydraulic pump unit, and a cylindrical control piston movably mounted by the control cylinder and linked to the swashplate, such that axial movement of the control piston is converted to transmission ratio-changing pivotal motion of the swashplate about a pivot axis intersecting the output shaft axis in orthogonal relation.
20. The continuously variable hydrostatic transmission defined in claim 19, wherein the ratio controller further includes first and second annular control chambers defined between the control cylinder and the control piston, such that hydraulic fluid pressure differentials in the first and second control chambers produce the axial movement of the control piston.
21 The continuously variable hydrostatic transmission defined in claim 20, wherein the first and second control chambers are defined by radially and axially opposed surface portions of the control cylinder and control piston.
22. The continuously variable hydrostatic transmission defined in claim 21, wherein the control cylinder is fixed in axial position while rotatingin unison with the control piston, swashplate and output shaft.
23. The continuously variable hydrostatic transmission defined in claim 22, wherein the manifold further includes 1) a third peripheral port, 2) a third internal passage leading from the third peripheral port to a third opening in the manifold radial face radially offset form the first and second openings, 3) a fourth peripheral port, and 4) a fourth internal passage leading from the fourth peripheral port to a fourth opening in the manifold radial face radially offset from the first, second and third openings, and the portplate further includes 1) a fifth annular cavity formed in the first radial face at a position in continuous fluid communication with the third opening, 2) a first internal fluid passage connecting the fifth annular cavity and the first control chamber in fluid communication, 3) a sixth annular cavity formed in the first radial surface at a position in continuous fluid communication withthe fourth opening, and 4) a second internal fluid passage connecting the sixth cavity and the second control chamber in fluid communication.
24. The continuously variable hydrostatic transmission defined in claim 23, wherein the transmission ratio controller includes a control valve in separate fluid connections with the second, third and fourth peripheral ports and selectively operable to create any one of the following conditions, 1) a hydraulic fluid pressure balance in the first and second control chambers to set an angular position of the swashplate to a desired transmission ratio, 2) a greater hydraulic fluid pressure in the first control chamber than in the second control chamber to pivot the swashplate about the pivot axis in a transmission ratio-increasing direction, and 3) a greater hydraulic fluid pressure in the second control chamber than in the first control chamber to pivot the swashplate about the pivot axis in a transmission ratio-decreasing direction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/418,692 US5678405A (en) | 1995-04-07 | 1995-04-07 | Continuously variable hydrostatic transmission |
| US08/418,692 | 1995-04-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2189846A1 true CA2189846A1 (en) | 1996-10-10 |
Family
ID=23659185
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002189846A Abandoned CA2189846A1 (en) | 1995-04-07 | 1996-02-07 | Continuously variable hydrostatic transmission |
Country Status (13)
| Country | Link |
|---|---|
| US (1) | US5678405A (en) |
| EP (2) | EP0763171B1 (en) |
| JP (1) | JP4202418B2 (en) |
| KR (1) | KR100399099B1 (en) |
| CN (1) | CN1149909A (en) |
| AT (1) | ATE185409T1 (en) |
| AU (1) | AU4917696A (en) |
| BR (1) | BR9606301A (en) |
| CA (1) | CA2189846A1 (en) |
| DE (2) | DE69612675T2 (en) |
| PL (1) | PL317329A1 (en) |
| TW (1) | TW328101B (en) |
| WO (1) | WO1996031715A1 (en) |
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| US6062022A (en) | 1997-04-25 | 2000-05-16 | General Dynamics Land Systems, Inc. | Continuously variable hydrostatic transmission including 1:1 ratio lock-up clutch |
| US6109034A (en) | 1997-04-25 | 2000-08-29 | General Dynamics Land Systems, Inc. | Continuously variable hydrostatic transmission ratio controller capable of generating amplified stroking forces |
| US5976046A (en) * | 1998-04-13 | 1999-11-02 | General Dynamics Land Systems, Inc. | Multi-range, hydromechanical transmission for application in high performance automotive drivetrains |
| AU7155398A (en) | 1997-04-25 | 1998-11-24 | General Dynamics Land Systems, Inc. | Multi- range hydromechanical transmission |
| US5896745A (en) * | 1997-04-29 | 1999-04-27 | General Dynamics Defense Systems, Inc. | Swashplate assemblies for infinitely variable hydrostatic transmissions |
| US6481203B1 (en) | 1999-06-10 | 2002-11-19 | Tecumseh Products Company | Electric shifting of a variable speed transmission |
| US7252020B2 (en) * | 2000-01-10 | 2007-08-07 | The United States Of America As Represented By The Administrator Of The U.S. Environmental Protection Agency | Vehicle drive-train including a clutchless transmission, and method of operation |
| KR100373157B1 (en) * | 2000-09-05 | 2003-02-25 | 이종한 | Continuously variable transmission |
| US6413055B1 (en) | 2001-02-02 | 2002-07-02 | Sauer-Danfoss Inc. | Swashplate position assist mechanism |
| US6510779B2 (en) | 2001-02-02 | 2003-01-28 | Sauer-Danfoss, Inc. | Electronic bore pressure optimization mechanism |
| US6381529B1 (en) * | 2001-06-07 | 2002-04-30 | Deere & Company | Control system for hydrostatic transmission |
| JP2004019835A (en) * | 2002-06-18 | 2004-01-22 | Yanmar Co Ltd | Hydraulic continuously variable transmission and power transmission apparatus |
| JP2004019836A (en) * | 2002-06-18 | 2004-01-22 | Yanmar Co Ltd | Hydraulic continuously variable transmission and power transmission apparatus |
| US7055507B2 (en) * | 2004-03-29 | 2006-06-06 | Borgwarner Inc. | Continuously variable drive for superchargers |
| SE529415C2 (en) | 2005-12-22 | 2007-08-07 | Atlas Copco Rock Drills Ab | Pulse generator and pulse machine for a cutting tool |
| PL206881B1 (en) | 2007-08-07 | 2010-10-29 | Henryk Więckowski | Hydrostatic non-threshold toothed gear |
| CA2716908C (en) * | 2008-02-29 | 2017-06-27 | Fallbrook Technologies Inc. | Continuously and/or infinitely variable transmissions and methods therefor |
| GB2494206A (en) * | 2011-09-05 | 2013-03-06 | Ransomes Jacobsen Ltd | Self-propelled grass cutting machine |
| US10167710B2 (en) * | 2014-04-10 | 2019-01-01 | Energy Recovery, Inc. | Pressure exchange system with motor system |
| SG11201803386VA (en) * | 2015-11-25 | 2018-06-28 | Kinetics Drive Solutions Inc | Load cancelling hydrostatic system |
| US10247178B2 (en) | 2016-03-28 | 2019-04-02 | Robert Bosch Gmbh | Variable displacement axial piston pump with fluid controlled swash plate |
| CN110067855A (en) * | 2019-03-13 | 2019-07-30 | 钟彪 | A kind of hydraulic stepless speed change transmission device |
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|---|---|---|---|---|
| US3204411A (en) * | 1964-04-06 | 1965-09-07 | Ford Motor Co | Hydrostatic drive |
| DE1653492C3 (en) * | 1966-10-20 | 1975-03-13 | Kopat Gesellschaft Fuer Konstruktion, Entwicklung Und Patentverwertung Mbh & Co Kg, 7323 Boll | Axial piston unit that can be used as a liquid pump and / or motor |
| US4493189A (en) * | 1981-12-04 | 1985-01-15 | Slater Harry F | Differential flow hydraulic transmission |
| DE3714888C2 (en) * | 1987-05-05 | 1994-10-06 | Linde Ag | Adjustable axial piston machine |
| EP0567598B1 (en) | 1991-01-14 | 1998-03-11 | Advanced Power Technology, Inc. | Hydraulic machine |
| US5486142A (en) | 1994-11-21 | 1996-01-23 | Martin Marietta Corporation | Hydrostatic transmission including a simplified ratio controller |
| US5540048A (en) | 1995-01-30 | 1996-07-30 | Martin Marietta Corporation | Continuously variable hydrostatic transmission including a pulse width modulation ratio controller |
-
1995
- 1995-04-07 US US08/418,692 patent/US5678405A/en not_active Expired - Lifetime
-
1996
- 1996-02-07 AU AU49176/96A patent/AU4917696A/en not_active Abandoned
- 1996-02-07 CA CA002189846A patent/CA2189846A1/en not_active Abandoned
- 1996-02-07 AT AT96905407T patent/ATE185409T1/en not_active IP Right Cessation
- 1996-02-07 PL PL96317329A patent/PL317329A1/en unknown
- 1996-02-07 EP EP96905407A patent/EP0763171B1/en not_active Expired - Lifetime
- 1996-02-07 WO PCT/US1996/001674 patent/WO1996031715A1/en active IP Right Grant
- 1996-02-07 DE DE69612675T patent/DE69612675T2/en not_active Expired - Lifetime
- 1996-02-07 BR BR9606301A patent/BR9606301A/en not_active Application Discontinuation
- 1996-02-07 EP EP99104657A patent/EP0918176B1/en not_active Expired - Lifetime
- 1996-02-07 KR KR1019960706976A patent/KR100399099B1/en not_active IP Right Cessation
- 1996-02-07 DE DE69604551T patent/DE69604551T2/en not_active Expired - Lifetime
- 1996-02-07 JP JP53027596A patent/JP4202418B2/en not_active Expired - Fee Related
- 1996-02-07 CN CN96190312A patent/CN1149909A/en active Pending
- 1996-02-27 TW TW085102267A patent/TW328101B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| EP0918176A3 (en) | 1999-08-11 |
| DE69612675D1 (en) | 2001-06-07 |
| KR100399099B1 (en) | 2003-12-24 |
| TW328101B (en) | 1998-03-11 |
| US5678405A (en) | 1997-10-21 |
| EP0918176A2 (en) | 1999-05-26 |
| WO1996031715A1 (en) | 1996-10-10 |
| AU4917696A (en) | 1996-10-23 |
| DE69612675T2 (en) | 2001-10-18 |
| DE69604551D1 (en) | 1999-11-11 |
| BR9606301A (en) | 1997-09-16 |
| PL317329A1 (en) | 1997-04-01 |
| EP0763171B1 (en) | 1999-10-06 |
| DE69604551T2 (en) | 2000-05-25 |
| CN1149909A (en) | 1997-05-14 |
| EP0763171A1 (en) | 1997-03-19 |
| KR970703504A (en) | 1997-07-03 |
| JP4202418B2 (en) | 2008-12-24 |
| EP0918176B1 (en) | 2001-05-02 |
| ATE185409T1 (en) | 1999-10-15 |
| JPH11500815A (en) | 1999-01-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |